bgiant
off to a rocking start
Member since September 2012
Posts: 13
|
Post by bgiant on Nov 6, 2012 2:51:00 GMT -5
Being new at this one of the things i want to do and what is actually being requested for by a bunch of people is placing a nice polished slab itself on a mount.
I have a covington 6" dual diamond unit with a trim saw, grinder, sanding, and polishing wheel. It is somewhat hard to work with for a larger slab but i am making it work to a degree.
The question i have is using the polish that comes in the syringes. I ahve a set of 10 of the syringes. The slabs i am working are not in rough stage but more of the kind that needs to be just polished but i have no idea how to use the syringes with it. Here are my questions:
Basing the following questions for a slab about 5" by 5"
1) Do i have to go through all 10 of the different polish grits? to polish the slab? 2)when do i know that i need to recharge the polish wheel? 3) how much water should be dripping on the wheel while polishing? 4) how long do i polish each slab per stage of the polishing? do i just water in the drip on the wheel or do i also need tyo add the coolant like you do for the trim saw?
|
|
|
Post by deb193redux on Nov 6, 2012 17:31:12 GMT -5
Usually with syringes, you only work with damp pads, because running water would wash off grit.
Is your unit the one with an expandable drum next to the polish plate?
Also, what is the grit range of these syringes. 10 levels sounds like more than necessary.
|
|
rykk
spending too much on rocks
Member since September 2011
Posts: 428
|
Post by rykk on Nov 8, 2012 21:30:20 GMT -5
You might get by with silicon carbide discs up to 3000 and then polishing on the polish head.
If you bought the slabs already cut, I seriously doubt that they are in a ready to polish stage. Sometimes you get some that are pretty smoothly cut and you *think* they're ready to polish. Trust me, after a while on the polish head you'll see all sorts of things your eye might not have caught. Even tiny scratches will stick out like a sore thumb. Best bet is to start at 220 grit and go up to 1500 or 3000 and then polish. That is if you can put the sanding discs on the polish head and clean very thoroughly especially between the last grit and placing the polish pad onto the disc.
The syringes sound like diamond pastes. I'm not sure that those are really good with a pad. The reason is that once you put a rougher mesh/grit on it - say, 220 - and then try to go to something finer like 400 or 600, the pad will be contaminated with the rougher grit and will mar the finer finish you're trying to get. These micro-scratches will show up upon polishing. Unless you use a different polish pad for each grit. From what I've gathered. the diamond pastes are used for lapping on a solid lap surface like tin, ceramic, or other gemstone lapping discs that are smooth and can be well cleaned between meshes. And the amount of paste used and the expense incurred doing big pieces like 5x5" would get high pretty quick, I'd think. Cabs don't use as much but a 5x5 slab polished on both sides would require as much diamond paste as probably like 30 or more typically sized cabochons.
If you intend to be polishing lots of slabs 3-5" and over, your best bet is to try to get hold of a vibrating lap. I've done slabs over 12" wide in my 20" Lortone. The neat thing is that you can get like 15-25 four to five inch slabs into one of these and do them all at the same time. A well documented problem with spinning laps is that it is very difficult to get a perfectly flat surface and you go to polish and there are low spots that don't polish. Especially the middles of slabs. I got my "jiggle pan" because of this problem so that I could get a perfectly flat surface to my slabs and nodule halves. There is a solid physics reason that the spinner laps don't do the middles well. Though, I reckon you could get around this by slightly dome shaping a slab but that's pretty hard to do staying consistent through all the grits such that the polished surface doesn't look funky and uneven. I reckon a very experienced and practiced hand is required to pull a dome polish off well on larger rocks. I've tried and there always ends up being flat spots that I couldn't see until midway through the polishing. C-ya, Rick
|
|